Such is the argument of Markus Imhoof’s beautifully filmed documentary, which follows assorted beekeepers – a placid old cheroot-smoker in an Alpine valley, an anxious beemagnate whose hives service a Californian mega-orchard, and others – through their daily rounds. The tone, abetted by John Hurt’s narration, is more meditative than strident; that makes the message all the more powerful.